Preparation of motor fuels having an octane number above 100



M r h 1 1968 R. G. CRAIG ETAL PREPARATION OF MOTR FUELS HAVING AN OCTANE NUMBER AB OVE 100 Filed March l 1966 ATTORNEY.

United States Patent Ofice Morton, Pa., assignors to Air Products and Chemicals, Inc., Philadelphia, Pa., a corporation of Delaware Filed Mar. 1, 1966, Ser. No. 530,989 4 Claims. (Cl. 208-65) ABSTRACT OF THE DISCLOSURE A full range reformate having an F clear octane number of about 90, and derived from hydrogenati-ve reforming over a platinum on alumna catalyst, is fractionally distilled to separate a heart cut having an IBP of at least 70 C. and EBP below 170 C. Sai-d heart out is reformed at about 535 C. at about 20 atmospheres H pressure at a H /hydrocarbon mol unit ratio of about at about 3 liquid volumes of hydrocarbon per volume of platinum on alumina catalyst and the second stage reformate is blended with the bottoms and forecut from the first stage reformate to provide full range gasolne having an F clear octane number above 100. Among multi-step routes toward full range gasoline having F clear octane above 100 using only refomning steps featuring platinum catalyst, this method has advantageously high yield and advantageously low deactivation rate for total platinum nventory.

This invention relates to the use of platinum catalyst for reforming at nonregenerative conditions for the prepzlgztion of liquid fuels having an octane number above For many years technologists have been aware of methods for preparing selected fractions of hydrocarbons having an octane number above 100. For example, con centration of aromatics by fractionation or extraction can provide a fraction having an octane number above 100. Refiners are primarily interested, however, in a full range stabilized gasoline making effective use of the components available in the raw petroleum. Nonregenerative reforming of virgin naphtha over platinum catalyst in the presence of a recycle gas containing a predominant volume of hydrogen has been a preferred route toward upgrading the octane number of virgin naphtha. During many years of industral rnprovements for nonregenerative (i.e., operation for periods of more than about 60 days prior to regeneration) reforming over platinum catalyst without resort to expeclients such as solvent extraction, the goal of producing full range gasoline having an octane number above 100 F clear has been often sought but never attained in practical and economically attractive operations.

By operating at a relatively low pressure, and even then accepting a correspondingly poor yield of reformate, it is possible to upgrade to desirably high octane number, but sueh low pressu-re requires frequent regeneraton. The increased investment required and greater operating costs for regeneration of platinum containing catalyst has largely discouraged such reforming operations requiring frequent regeneration.

Although reliance merely upon regeneratve reforming over platinum has been a desired goal of petroleum proc- 3,374,167 Patented Mar. 19, 1968 ess engineers, greater economy in producng fue1 having an octane number about 100 has previously been attainable by resort to one or more techniques such as solvent extraction, thermal reforming, regenerative reforrning, purification of hydrogen, and/ or other techniques to supplement reforrning over platinum. Desired high octane fuels can also be obtained by increased severity of reforrning obtained by increasing temperature, or the acidity of the catalyst or by decreasing pressure or space rate, but these procedures also entail increased incremental costs per barrel of -reformatie. Various proposals have been made concerning the boiling points of fractions treated at va-rious conditions, but the marginal costs of supplemental fractonal distillations have dscouraged. industrial use of most such experimental procedures.

In the operation of a reformer, it is very advantageous to maintain substantially the same operating conditions throughout a number of months, and to adjust the temperature upwardly to maintain the desired octane number of reformate. The designation of F. per barrel of feedstock per pound of catalyst has become a unit indicative of the stablity of the catalyst at selected conditions. A corresponding metric unit is C/L/g. catalyst, each F./bbl./pound of catalyst equalling about 1.59 C./l./g. of catalyst. It is necessary to design the process to permit only a limited increase in temperature from the beginning of a run until regeneration is required.

. In accordance with the present invention, a motor fuel having an octane number (F clear) above 100 is prepared by subjectng a virgin naphtha to reforming at con ditions providing an octane number of the reformate within the range from about 85 to about 93 F clear octane number, and this reformate is subjected to distilla tion to prepare a heartcut having the approximately 72- 162 C. boiling point range, subjecting such heartcut to the severe reforming hereinafter specified, and blending the thus prepared fuel with the bottorns and forecut from the distillation of the reformate from the first stage of reforming. The thus blended fuel is ;a stabilized, full range gasoline having an octane number above 100. Inasmuch as the selected heartcut is largely free of those components having the highest tendency to produce coke in the reforming operation, this cut can be readily re forrned at the indicated high severity without undue loss of catalyst activity and without necessitating frequent catalyst regeneration.

In preferred practice of the invention, the selected reformate heartcut subjected to further severe reforming is one having an initial boiling point within the range from about C. to about C. whereby normal hexane and lower boiling paraflns are substantially excluded; and an end boiling point in the range from about C. to C., whereby polycyelic hydrocarbons are substantially excluded. The process conditions include: controlling the hydrogen to hydrocarbon unit mol ratio within the range from 3 to 8, wherein the hydrogen purty of the recycled gas is rnaintained by withdrawing a portion of the efiuent gas; controlling the space velocity within the range of 1 to 3 volumes of liquid hydrocarbon per volume of catalyst per hour whereby the capital investment in catalyst is not prohibitive; controlling the pressure of the reforming zone within the range from 15 to 30 atmospheres, whereby operation for periods longer than 60 days between regenerations are feasible; and controlling the temperature within the range from 480 C. to 550 C., whereby the catalyst stability is maintained throughout a series of regenerations, permtting the ultimate useful life of the platinum catalyst to be adequate.

In the drawings, the figure is a self-explanatory flow sheet.

The invention is further clarified by reference to a plurality of examples illustrating a few of the permssible varables within the broadest concept of the invention.

Example 1 A crude petroleum is distilled to provide a virgin naphtha having characteristics as follows.

Specfic gravity g./ml 0.7724 ASTM distillation, C.:

Initial 113 124 127 20 134 30 140 40 147 50 152 60 158 70 164 80 171 90 181 95 191 End point 201 Dry point 201 Recovery, vol. percent 98.7 Octane numbers:

F clear 40.1 F +3 cc. TEL 67.1 F clear 42.0 F +3 cc. TEL 67.2 Reid vapor pressure 0.6 Sulfur, p.p.m. 19 Nitrogen, p.p.m. None Chloride, p.p.m. Less than 1 Arsenic, p.p.b. Less than 1 Lead, p.p. b 10 H 0, p.p.rn 1 81 Bromine No. 0.2 Chemical composition, volume percent: Para.fins 50.1

Normal paraflns, total 18.9

Isoparaffins, total 31.2 Olefins 0.0 Naphthenes 37.4

C ring 5.2

C ring 27.7

Polycyclic paraflns 4.5 Aromatcs 12.5

Indane, indene, naphthalene 0.3

Total 100.0

1 Dried before use.

This naphtha is subjected t0 reforming over a platinum on alumina catalyst to produce a reformate havng an F octane rating of about 90.5. T his full range reformate is distilled to separate it into 3 ractions, a forerun containing hydrocarbons having an end boiling point of about 70 C. and heartcut having a bolling point range from 70 C. to 165 C., and a bottoms fraction having an initial boilng point of about 165 C. The characteristics of the full range reformate and three fractions are approximately as follows:

Full range Fore- Heart- Bottoms reformate out: cut

Speelfic Gravlty, g./ml 0. 7941 0. 6637 0.7981 0. 8822 ASTM Dlstillation, 0.:

41 32 103 170 71 41 175 90 43 117 177 113 47 122 179 126 50 127 181 53 131 183 143 57 135 184 60 139 188 158 63 143 192 167 66 149 199 186 71 154 213 208 77 159 233 236 86 164 266 Dry Point 236 84 163 266 Recovery, Vol. Percent- 97.2 97.0 98.0 98.8 Octane Nurnbers:

90. 5 74. 6 86. 7 102.1 98. 8 92. 3 96. 8 104. 7 78. 8 72.3 76. 7 90. 9 89. 3 92. 7 87. 5 98.0 Reid Vapor Iressure 6. 2 12. 9 1. 0 0.4 Sulfur, p.p.m 20 17 9 22 Nitrogen, p.p.m None None 0. 4 0.7 Chloride, p.p.m 1 1 3 Arsenic, p.p.b 4 7 5 Lead, p 1) 10 10 10 10 H 0, p.p.m.- 9 38 1 122 107 Bromine No 2. 3 5. 7 2. 0 1. 3

1 Dried before second stage reforming.

HEAR'ICUI Volume Percent oi Heartcu: 90.5 F1 reiormate O6 parafns 1. 0 0.61 0 paraflns.- 10.6 6. 51 0x paraflns...- 13. 3 8.17 09 paraflns 11.9 7. 31 010 params... 5. 5 3.38 011 paraffins 0.5 0.31 012 parafins.- O ring naphthenes 7. 0 4. 30 C ring naphthenes. 0. 6 0. 37 0. 5 0.31 10.1 6. 20 20. 7 12. 70 17.1 10. 79 0. 8 0. 49 Indane 0. 4 0.25

Total 100. 0 61. 40

F1 Clear Octane No The reforming catalyst employed consists of alumina pellets about 1.6 mm. diameter and about 4 to 5 mm. long, having a platinum content of 0.50%, 21 packed bulk density of 840 g. per liter, a su-rface area of 260 rn./g., a pore volume of 0.40 cc./g., ar1 average pore radius of about 31 angstroms, a crushing strength of 4.4 kg. and an ignition loss at 760 C. of 2.5%.

The 103-163 C. heartcut is subjected to severe nonregenerative reforrning over a platinum on alumina catalyst at a temperature of 500 C. at a space rate of one and at a hydrogen to hydrocarbon ratio of 8 to 1. The reformate obtained by such severe reforming is admixed with the forecut and bottorns from the previous distillation, and the blend is a full range gasoline having -an octane number above 100.

Examples II-V A heartcut from a reformate having characteristics re sernbling the heartcut of Example I was subjected to high g conditons permit clear octane of at least As prevously explained, the operatin greater severty, whereby an F III IV dicated in the followng table Example No Hrs. on Cat tor Run Tota1 Hrs. on Catal Operatng Conditi 75 the catalyst fewer than six t1mes per year (nonregenera tive operation for more than 60 days) are attainable at the 103.8 octane level appropriate for achieving a blend having an F octane number of at least 100.

One basis of such experimental data, it was concluded that the concept of severe reforming of the selected heartcut and thereafter blending the ungraded heartcut with the forerun and bottoms provides an eective method for achieving high octane gasoline.

Example VI A virgin naphtha is distilled to separate a heartcut having a boiling point range from about 75 C. to about 160 C. This heartcut is mixed with 3 mols of hydrogen and passed at a temperature of 520 C. at a pressure of 15 atmospheres over a platinum on alumina catalyst at a space rate of about one. The reformate thereby produced has an octane rating of about 103 F clear. The forerun and bottoms are separately reformed at conditions milder than required for the heartcut, and the blend with the severely reforrned heartcut is a full range gasoline having an F clear octane number of 100.1.

The same vrgin naphtha is reformed to provide a refor-mate having a 93 F clear octane, and the 75- 160 C. heartcut is subjected to severe reforming to provide a fraction having an F clear octane of 103, and blended with the forecut and bottoms to provide a blend having an F clear octane number of 100.1. The yield of 100 octane gasoline is greater when the reformate heartcut is subjected to the severe reforming than when the naphtha is subjected to such severe conditions. Moreover, the deactivation rate for the catalyst inventory is more favorable if the full range naphtha is first reformed to the 93 F clear reformate prior to separating the heartout for severe reforming.

Example VII A variety of reformates derived from a variety of naphthas are evaluated to estimate the suitability of the severe reforming method. Each full range reformate has an F clear octane number within the range from 85 to 93. The heartcut from 75 C. to 160 C. from each reformate is subjected to severe reforming to provide an upgracled fraction having an F clear octane number within the range from 102 to 105. Higher octane number of the severely reformed heartcut is necessary when the initial reformate is closer to the lower limit. In each case, a blend having an F clear octane in the range from 100.1 to 101 is acheved.

The quantity of C C hydrocarbons produced at the high severity reforming is quite large, especially in relation to the quantity of hydrogen generated. In order to achieve nonregenerative conditions in the severe reforming stage, supplemental hydrogen must be introduced to preserve an adequately high hydrogen purty. The costs of rnaintainng a hydrogen to liquid hydrocarbon ratio such as 8 become excessve if the hydrogen purty is quite low, such as 33% by volume of recycle gas. By utilizing a hydrogen rich stream available in excess from the rst stage reformer, and supplying it to the severe supplemental reformer at a rate equivalent to the gas production in the severe reformer while withdrawing an effluent gas stream at a rate equivalent to the gas produc tion in the severe reformer, the recycle gas for the severe reformer can have an acceptable proportion of hydrogen. As indicated in connection with Examples II-V, supplemental hydrogen can be directed through the severe re former if r1ot operating in close proximity to the first stage reforrner.

The hydrogen to liquid hydrocarbon unit ratio is thus maintained between 3 and 8. The total pressure is maintained within the range from 15 to 30 atmospheres. The reforming temperature is at least 480 C. but less than 550 C. Space rate is regulated from 1 to 3 volumes of heartcut per volume of catalyst per hour.

Obviously many modifications and variations of the inventon as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

What is claimed is:

1. In the method in which the octane number of a liquid hydrocarbon is upgraded by treatment over a platinum catalyst under superatmospheric hydrogen pressure at conditions permitting continued operation for more than sixty days prior to catalyst regeneration, the improvement which consists of the combination of: fractionating a primary full range reformate of liquid hydrocarbons of 85 to 93 octane (F clear) to provide a heartcut haviug an initial boiling point of at least C., whereby normal hexane and lower boiling paraflins are substantially excluded, said cut having an end boiling point below 170 C., whereby polycyclic aromatics are substantially excluded; reforming said heartcut over supported platinum catalyst at severe conditions including hydrogen to liquid hydrocarbon unit ratio in the range from 3 to 8, space velocity from 1 to 3 volumes of liquid per volume of catalyst per hour, temperature in the range of 480 C. to 550 (3., and pressure from 15 to 30 atmospheres; and blending the reformed heartcut with the remaining liquid forerun and bottorns components of the fractionated primary reformate to obtain a full range gasoline havng an F clear octane number greater than 100.

2. The method of reforming of claim 1 in which said primary reformate is one obtained by reforming a naphtha over a platinum catalyst under superatrnospheric hydrogen pressure at conditions permitting continued operation for more than sixty days prior to catalyst regenera-tion in preparing a full range prirnary liquid reformate having an F clear octane number within the range of to 93, and in which said heartcut after severe reforming as defined has an F clear octane number greater than 102.

3. The method of claim 2 in which at least a portion of the hydrogen-rich gas produced in reforming naphtha to an octane number from 85 to 93 is transferred to the inlet to the zone for severe reforming of said heartcut, and an approximately equal volume of gas is withdrawn from the effluent from said zone for reforming said heartcut, whereby the separate recycle gas streams are separately maintained at different hydrogen purities.

4. The method of claim 2 in which a naphtha is reformed to an octane number of about 90, a heartcut having a boiling point range from about 103 C. to about l63 C. is separated from such reformate, the heartcut is reforrned at a temperature of about 535 C. at a space rate of about 3 volumes of liquid per volume of catalyst per hour -at a pressure of about 20 atmospheres at a hydrogen to liquid hydrocarbon unit ratio of about 10 to provide a reformate, and such reformate is blended with the other fractions from the full range reformate to provide said full range gasoline having an F clear octane number greater than 100.

References Cited UNITED STATES PATENTS 2905621 9/1959 Bauer et al. 208-65 ABRAHAM RIMENS, Prmary Examiner.

DELBERT E. GANTZ, Examner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CURRECTION Patent NO. 3374,167 March 19, 1968 Robert G. Craig et al.

It is certified that error appears in the above dentfed patent and that sa.id Letters Patent are hereby corrected as shown below:

Column 1, line 65, for "regenerative" read nonregenerative column 2, line 2, for "about" read above column 4, "second table, thrd column, line 13 thereof, for "10. 79" read 19.49 columns 5 and 6, in the table, fourth column, line 4 thereof, for "5l2"'rad 513 column 5, last table, frst column, line 5 thereof, for "F clear" read F clear column 7, line 4, for "One" read On the 2 Sgned and sealed this 22nd day of July 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attestng Officer Commissioner of Patents 

